Technical Field
The present disclosure relates to an electrical protection device and to a method of protecting an electronic device.
Description of the Related Art
As is known, frequently used in electronic apparatuses are protection devices that basically have the purpose of preventing current overloads and any damage that might derive therefrom.
Conventional fuses are very commonly used, which perform in an excellent way the function of protection; however, they are irreversible. Evidently, full functionality of the protected devices cannot be restored until the blown fuses are replaced.
To get over this problem, use of so-called electronic fuses (e-fuses) is often preferred. Devices of this type exploit power MOSFETs configured to limit the maximum current that may be transferred to a load to be protected. Normally, however, onset of an overcurrent leads to saturation of the power MOSFET and modifies the working point of the electronic fuse in a substantial and permanent way, at least until a reset operation is carried out. As shown in FIG. 1, in practice, as long as the power MOSFET remains in the ohmic region, as the current required by the load (designated by I′) increases the electronic fuse is able to supply a current I0 that is limited to a protection value ITRIP. An overcurrent may send the power MOSFET into saturation. The maximum current is effectively limited to the protection value ITRIP, but then the power MOSFET remains in saturation and a maximum saturation current ISAT that can be provided by the electronic fuse is lower than the protection value ITRIP. To restore the initial working conditions, also in this case a reset operation is necessary. It is evident that, if the normal working conditions of the protected device include a current between the maximum saturation current ISAT and the protection value ITRIP, after tripping of the electronic fuse the protected device cannot be supplied properly until reset is carried out.